1. Field of the Invention
The invention relates in general to an anti-static agent and the method of preparing the anti-static agent, and more particularly to a polyether compound containing a diamino group at the end, a diacid, and a diol polymerized and condensed to form an anti-static agent. This anti-static agent contains a high molecular weight and a long endurance.
2. Description of the Related Art
Most of the anti-static agents made of polymer materials are additive type. The anti-static agents can be categorized into two groups: one group with a low molecular weight, that is, a conventional surface active anti-static agent; the other group with a high molecular weight. Being washed or wiped, the anti-static property of the anti-static agent with a low molecular is easily deteriorated, or even lost. In addition, the temperature and humidity dependence of the anti-static agent is strong, and the surface property is poor. On the contrary, due to the polymer structure, the anti-static agent with a high molecular weight is compatible with other polymers, and thus, the second group of anti-static agent has a long endurance.
The conventional polyester anti-static agent with a high molecular weight is normally categorized into two groups. One group is formed by using a sulfonate or a polyethylene oxide (PEO) with a high molecular weight coated on the surface of the polyester or added inside the polyester. For example, in Japanese Patent No. 5,262,460, a PET is mixed with a PEO of 5000 g/mole to 16000 g/mole to obtain an anti-static resin. In U.S. Pat. No. 5,010,193, a PET is mixed with a copolymer with an ethylene oxide group of 2000 g/mole to 50000 g/mole to improve the anti-static property and compatibility. Or in U.S. Pat. Nos. 5,194,327 and 5,182,169, a sulfonate with a high molecular weight is coated on the surface of a polyester to improve the disadvantages in the anti-static agent with a low molecular weight, such as opacity and surface cake. Thus, the anti-static property is enhanced.
In the other group, the polyester is mixed with a PEO or a dicarboxy phenyl sulfonate to improve the hydrophile and obtain the anti-static polyester. For example, in U.S. Pat. Nos. 5,130,073, 5,064,703, 4,713,194, and 4,506,070, a polyester is condensed with a PEO to obtain a hydrophilic polyester. However, due to the incomplete reaction between the PEO and diacid, an anti-static agent with a high molecular weight is not easily to be formed.
In U.S. Pat. Nos. 4,943,510, 5,051,475, 4,468,433, and 450,607, a polyester is mixed with a dicarboxy phenyl sulfonate or a PEO to obtain a hydrophilic polyester. However, the physical and anti-static properties of polymers in this kind of anti-static agent is poor.